Stratigraphic relationships of minerals and organic matter in the trona-bearing lower Wilkins Peak Member and the Tipton Shale Member of Wyoming's Green River Formation are presented as histogram plots with depth. Oil yields and x-ray diffraction peak heights of 17 minerals are presented for samples from an oil-shale core drilled near the depositional axis of the Green River Basin. The mineral and oil-yield profiles picture graphically a remarkable lacustrine sedimentary sequence involving the deposition of hydrogen-rich organic matter in oil shale and the development of sodium carbonate minerals. The emphatic difference in mineralogy between the Tipton Shale and the Wilkins Peak Members is evaluated. In addition, the major occurrence of the mineral nahcolite (NaHCO/sub 3/) heretofore noted only as a single trace in Wyoming's Green River Formation is reported.